Anna was adopted by owner Jimy Negrotto from Plaquemines Animal Welfare Society (P.A.W.S.) in 2009. The difficulties that black dogs have in finding adoptive homes is known to shelter workers as "black dog syndrome" or "black dog bias."

Onyx and Russell — kittens just shy of a year old — meow insistently whenever someone approaches their cage at Jefferson Feed Pet & Garden Center. Take them out and they turn into purring furballs, eager to be held, petted and played with. Like the other cats at "Meow Town" inside Jefferson Feed, Onyx and Russell are up for adoption by Friends of the Jefferson Parish Animal Shelter (JPAS), but the numbers show that — despite their similar personalities — one is more likely to be adopted than the other.

Russell is a bright orange cat, while Onyx's coat is solid black — and that makes all the difference, shelter professionals say.

"Black animals just don't stand out," says Julie Bowen, a volunteer with the organization. "And some people still have that superstition that black cats are bad luck."

That day, the JPAS has so many black cats and dogs available that the group is holding a "Black and White Ball" at the feed store. Black dogs and cats are only $12 to adopt — and you can get a second cat free. Anyone adopting a black or black-and-white animal will go home with lots of extras, including inoculations, freebies and a free vet visit a year down the line. It's the second time the volunteer group has held a promotion designed to help black animals find homes. The first attempt had disappointing results.

"It didn't make a difference," Bowen says. "But you have to try."

The plight of Onyx, and animals like him, isn't unique to south Louisiana. Homeless dogs and cats with black fur make up the plurality of adoptables in shelters across the country, according to the Humane Society of the United States. The phenomenon is common enough to have its own names: BDS and BCS, for "black dog syndrome" and "black cat syndrome." Every shelter we spoke to in the New Orleans area is well aware of it.

Why the prejudice? There's no empirical data, but shelter workers cite several factors:

• Black animals are harder to photograph effectively, so they don't look as appealing on Petfinder.com and other adoption websites.

• Many shelters have poor or weak lighting in the kennel areas, putting dark-colored animals at a disadvantage.

• Superstition: The color black is still associated with bad luck, particularly with cats.

• Large black dogs appear more menacing to some people than do dogs with lighter fur.

• It's harder to read a black animal's expression at first glance.

• People are leery of black fur getting on the furniture.

• ... Uh ... no one really knows.

"I quit trying to figure it out," Bowen says.

"If you ask a potential adopter, you won't get an answer, because they really don't know why," says Jessica Harris, volunteer coordinator at the St. Tammany Humane Society, a no-kill shelter in Covington. "They're very hard-pressed to give you an answer. Certainly there's no difference temperament-wise [with black animals]."

Whatever the reason or reasons, the end result is happy, healthy animals being overlooked, and, sadly, euthanized in greater proportions than the general stray animal population.

Julie Bowen, a volunteer with the Friends of the Jefferson Parish Animal Shelter, holds Onyx the cat. At the group's recent "Black and White Ball" adoption event, animals with black or black-and-white fur had lower adoption fees. Despite the incentive, it was Onyx's cagemate, an orange cat named Russell, that got adopted that day.

Jacob Stroman, programs director for the JPAS, is sitting on the floor in the entryway at Jefferson Feed playing with Magic, a mutt with black fur, hoping some potential adopter might notice Magic's alert eyes, doggy smile and eagerness for belly rubs. Stroman says the shelter currently has five black Labrador retrievers looking for homes.

"People pay hundreds of dollars elsewhere for a Lab," Stroman says. "They're the most popular dog in America, and when we get them, the yellow and the chocolate Labs go first."

At the St. Tammany Humane Society, Harris looks down the first aisle of "Adoption Row." Of the 25 dogs there, "about half are black," she says. "I used to work in adoptions, and when people would walk down that first row and see all the black animals — in their minds, they kind of lump them together."

It's a similar story at the Louisiana Society for the Prevention of Cruelty to Animals (LA/SPCA) in Algiers. "I've seen people walk through the dog room and they don't even see black dogs," says Ana Zorrilla, the group's CEO. "They just walk right past to another dog."

Indeed, the numbers are against black animals. In 2011, 40 percent of the cats taken in by the LA/SPCA were predominantly black, Zorrilla says. Of those, 35 percent were adopted; 40 percent, euthanized. The numbers are only slightly better for black dogs — 28 percent of the LA/SPCA's dogs last year were black or mostly black. The adoption-euthanasia numbers were about equal for canines — between 27 and 30 percent.

"We've done some specific promotions," Zorrilla says. "We've tried different prices for black animals. We've given away pet products when black animals are adopted — a carrier, leash and collar. We did [a promotion] around the NFL: black and gold. We had black animals up for adoption at a 'little black dress' event we held. There's always opportunities to do more."

Last year, the St. Tammany Humane Society slashed adoption fees on black dogs to $5. It helped, a little, "but not as much as we'd hoped for," Harris says.

On the LA/SPCA adoption floor, the number of black animals is apparent, but there's a subtler message there as well. A look at the kennel cards shows that many of the black animals have been there a long time. Jimmy, a sleek black cat with beautiful gold eyes and a friendly, goofy disposition, has been on the adoption floor for more than three months. That's not uncommon.

"If we get multiples of the same breed, the black one is going to sit on the adoption floor longer — some significantly longer," Zorrilla says. "And a black pit bull is going to sit at least two or three weeks longer than a brindle or a light-colored dog. At least two to three weeks longer."

Shelter workers say animals with black fur, like these cats, tend to blend together in the eyes of potential adopters.

In her book Animals Make Us Human, animal behaviorist Dr. Temple Grandin says a "handful of studies" indicate "black cats are more social overall, whether it's with other cats or humans." But Grandin doesn't cite what those studies are, nor who conducted them. Plenty of websites attempt to draw a link between animal fur color and its personality and temperament, but none of the shelter workers contacted for this story agree with Grandin in regard to either cats or dogs. "It has more to do with their upbringing," Zorilla says.

Besides adoption incentives, shelters have tried to come up with other ways to show off animals with dark fur. Since they can be harder to photograph, many shelters welcome volunteer professional photographers who have time to adjust camera settings and lighting so the texture of the animals' fur is clear (and that their eyes aren't reflecting the camera flash). At the LA/SPCA, shelter workers and volunteers place colorful blankets in cages containing black cats to make the felines more eye-catching.

Animal shelters across the country have grappled with trying to find solutions. In Hoboken, N.J., Daytona Beach, Fla., Portland, Ore. and other cities, shelters have cut adoption fees for black animals. Winnepeg, Manitoba, Canada and Boise, Idaho are two cities that have established "black dog clubs" for adopters. And independent groups have formed to find homes for black animals: Black Pearl Dogs, Black Cat Rescue, Black Cat Animal Rescue and many others.

Jacob Stroman, left, is programs director for the Jefferson Parish Animal Shelter. Stroman says finding adoptive homes for black dogs is a continual challenge. Early in March, the shelter had five black Labrador retrievers in search of homes.

Heather Rosenwald, a Minnesota animal lover, created a website called Start Seeing Black Dogs (www.startseeingblackdogs.com), which urges shelters and their volunteers to "think outside the crate" and come up with "creative, inspirational and fun ideas" to showcase black canines. Among Rosenwald's tips: "bedazzle" black dogs with colorful vests and neckerchiefs; hold "black dog walks" at public events; and avoid names that reinforce the animals' fur color. Midnight, Blackie, and, yes, Onyx might not be the best choices.

(A glance at Petfinder.com's list of adoptable animals in the New Orleans area demonstrates the problem: black animals there tend to look alike in photographs, many taken by untrained volunteers, and many have names like Voodoo, Chaos, Shadow, Phantom, Black-Black and Mr. Blacky Night.)

Marti Houge is founder of One Starfish Homing Connections, a rescue in Columbus, Wis. that specializes in helping elderly, abused, and special-needs dogs, as well as purebreds rescued from puppy mills. Several years ago, she began the Black Beauty Bandana Project, which provides shelters with colorful neckwear to dress up black dogs. "Shelters have told us it makes a real difference at adoption days," Houge says. Among the Bandana Project's clients is Friends of the Jefferson Parish Animal Shelter; Stroman says the neckwear does indeed make a difference, as does posting videos of the animals online, not just photographs.

"We had a dog that we'd had for a while," Stroman says, "and within an hour-and-a-half of putting up a video, we had someone wanting to adopt him."

Back at Jefferson Feed, an elderly couple has been examining all the cats up for adoption, and they've made a decision. After months of waiting in his cage with Onyx, Russell is finally going home.

As the adopters fill out paperwork, Bowen makes a brief pitch for Onyx as well, but the couple isn't interested in adopting two cats, and Bowen drops the matter.

Russell is put in a carrier, and Onyx watches as his orange friend leaves the cage for the last time.

Shortly after the Black and White Ball is over, Friends of JPAS makes the decision to continue the $12 adoptions for another week. Their adoptable dog areas are at full capacity.